High field magnetization of the frustrated one-dimensional quantum antiferromagnet LiCuVO₄

Abstract

We have investigated the high field magnetisation of the frustrated one\ndimensional compound LiCuVO4. In zero field, LiCuVO4 undergoes long range\nantiferromagnetic order at T_{N} ~ 2.5 K with a broad short range Schottky type\nanomaly due to one dimensional correlations in the specific heat at 32 K.\nApplication of a magnetic field induces a rich phase diagram. An anomaly in the\nderivative of the magnetisation with respect to the applied magnetic field is\nseen at ~ 7.5 T with H ll c in the long range order phase. We investigated this\nin terms of a first experimental evidence of a middle field cusp singularity\n(MFCS). Our numerical DMRG results show that in the parameter range of LiCuVO4\nas deduced by inelastic neutron scattering (INS), there exists no MFCS. The\nanomaly in the derivative of the magnetisation at ~ 7.5 T is therfore assigned\nto a change in the spin structure from the ab plane helix seen in zero field\nneutron diffraction.\n